Typical fossil fuel power plants, and other incineration apparatus, such as waste incinerators, produce large amounts of bottom ash, left as residue in a combustor from the fuel combustion, and fly ash, exiting with gaseous combustion products in (flue gas) stack emissions. The ash products may contain substantial amounts of toxic matter, such as elemental metals, metal oxides, sulfur, and chlorine, considered hazardous to the environment. The ash composition often results in restrictions on the disposal of the ash and may require substantial expense in collecting and hauling the ash to a hazardous waste site which may be inconveniently located and have considerable deposit fees, and such a site itself remains an environmental hazard,
Suggestions have been made for processing ash by various treatments to a form intended to result in a reduced hazard with less expense of disposition. These have not been adopted to a large extent and there remains a need and desire for more effective and efficient treatment.